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排序方式: 共有241条查询结果,搜索用时 909 毫秒
71.
Qingyun Kang Mingyu Chu Prof. Panpan Xu Dr. Xuchun Wang Shiqi Wang Prof. Muhan Cao Prof. Oleksandr Ivasenko Prof. Tsun-Kong Sham Prof. Qiao Zhang Prof. Qiming Sun Prof. Jinxing Chen 《Angewandte Chemie (International ed. in English)》2023,62(47):e202313174
Chemical upcycling that catalyzes waste plastics back to high-purity chemicals holds great promise in end-of-life plastics valorization. One of the main challenges in this process is the thermodynamic limitations imposed by the high intrinsic entropy of polymer chains, which makes their adsorption on catalysts unfavorable and the transition state unstable. Here, we overcome this challenge by inducing the catalytic reaction inside mesoporous channels, which possess a strong confined ability to polymer chains, allowing for stabilization of the transition state. This approach involves the synthesis of p-Ru/SBA catalysts, in which Ru nanoparticles are uniformly distributed within the channels of an SBA-15 support, using a precise impregnation method. The unique design of the p-Ru/SBA catalyst has demonstrated significant improvements in catalytic performance for the conversion of polyethylene into high-value liquid fuels, particularly diesel. The catalyst achieved a high solid conversion rate of 1106 g ⋅ gRu−1 ⋅ h−1 at 230 °C. Comparatively, this catalytic activity is 4.9 times higher than that of a control catalyst, Ru/SiO2, and 14.0 times higher than that of a commercial catalyst, Ru/C, at 240 °C. This remarkable catalytic activity opens up immense opportunities for the chemical upcycling of waste plastics. 相似文献
72.
Atomic-Level Regulation of Cobalt Single-Atom Nanozymes: Engineering High-Efficiency Catalase Mimics
Dr. Yuanjun Chen Dr. Bing Jiang Prof. Haigang Hao Dr. Haijing Li Chenyue Qiu Xiao Liang Qingyun Qu Zedong Zhang Prof. Rui Gao Prof. Demin Duan Dr. Shufang Ji Prof. Dingsheng Wang Prof. Minmin Liang 《Angewandte Chemie (International ed. in English)》2023,62(19):e202301879
Nanozymes aim to mimic the highly evolved active centers of natural enzymes. Despite progress in nanozyme engineering, their catalytic performance is much less favorable compared with natural enzymes. This study shows that precise control over the atomic configuration of the active centers of Co single-atom nanozymes (SAzymes) enables the rational regulation of their catalase-like performance guided by theorical calculations. The constructed Co-N3PS SAzyme exhibits an excellent catalase-like activity and kinetics, exceeding the representative controls of Co-based SAzymes with different atomic configurations. Moreover, we developed an ordered structure-oriented coordination design strategy for rationally engineering SAzymes and established a correlation between the structure and enzyme-like performance. This work demonstrates that precise control over the active centers of SAzymes is an efficient strategy to mimic the highly evolved active sites of natural enzymes. 相似文献
73.
应用串联氮杂Wittig反应设计合成了一系列新的2-烷氨(芳氧)基-3,8-二苯基-5-芳基-6-甲基-5,8-二氢-4H-吡唑并[4',3':5,6]吡喃并[2,3-d]嘧啶-4(3H)-酮衍生物。通过氢核磁共振谱仪(1H NMR)、傅里叶变换红外光谱仪(FTIR)和元素分析等方法对所合成的化合物进行了结构表征,用X射线单晶衍射确证了化合物2-二正丙基氨基-3,8-二苯基-5-(4-甲基苯基)-6-甲基-5,8-二氢-4H-吡唑并[4',3':5,6]吡喃并[2,3-d]嘧啶-4(3H)-酮(Ⅲi)晶体结构。室内的杀菌和杀虫活性测试结果表明:目标化合物具有一定的杀菌活性,其中部分化合物对黄瓜灰霉菌(Botrytis cinereapers)在50 mg/L剂量下抑制率达到90%以上,显示了优异的杀菌活性;对水稻褐飞虱无明显的杀虫活性,但发现对粘虫具有较高的杀灭效果,大多数抑制率达到90%以上。 相似文献
74.
以多壁碳纳米管(MWCNT)为模板,通过正硅酸乙酯(TEOS)的水解缩聚反应制得MWCNT@SiO2纳米同轴电缆.采用透射电子显微镜(TEM)、扫描电子显微镜(SEM)和电化学测试对样品的形貌、结构及电化学性能进行表征.结果表明,MWCNT表面包覆了一层厚度均匀的多孔SiO2层,利于其获得较好的储锂性能.作为锂离子电池负极材料,MWCNT@SiO2纳米同轴电缆表现出了较高的比容量和较好的循环性能.在100 m A/g电流密度下经过80次循环,MWCNT@SiO2纳米同轴电缆的放电比容量仍高达431.7 m A·h/g,高于石墨材料的理论比容量(372 m A·h/g). 相似文献
75.
建立流动注射分析法测定工业废水中氰化物浓度的方法。水样及试剂在蠕动泵的作用下进入管道,先后经过蒸馏模块与化学模块,最后进入检测模块得出系统处理后的数据。通过对实际样品和标准样品的分析得出该方法的检出限为1.55μg/L,相对误差小于5%。氰化物质量浓度在0~500μg/L范围内与信号值呈良好的线性关系,线性相关系数r2=0.999 9。测定结果的相对标准差为0.1%~3%(n=4),加标回收率为93.3%~102.0%。该方法实现了自动进样、在线蒸馏,具有分析速率快、试剂耗量少等优点,可用于水和废水中总氰化物的测定。 相似文献
76.
In this paper, we modify the original physiological model of artificial pancreas by introducing the insulin secretion time
delay. The non-resonant double Hopf bifurcation is analyzed by the Center Manifold Theorem and Normal Form Method. Numerical
results supporting the theoretical analysis are presented in some typical parameter regions. It is shown that the critical
value of technological delay and the area of death island of the non-resonant double Hopf bifurcation in the modified model
are far less than those in the original model. This implies that when the secretion delay appears, the smaller technological
delay can induce the double Hopf bifurcation. In addition, the region IV with complex coexisting bi-stability also decreases sharply. Furthermore, the rich dynamics such as various period, quasi-period
and chaotic behaviors are found when some key parameters are changed. The obtained results can have important theoretical
guidance for the diagnosis and treatment of diabetes patients. 相似文献
77.
Zhang Sen Liu Qi Wang Wei Lv Hangbing Zuo Qingyun Wang Yan Li Yingtao Lian Wentai Long Shibing Wang Qin Liu Ming 《Applied Physics A: Materials Science & Processing》2011,105(4):1003-1009
The performances of bulk-heterojunction (BHJ) solar cells are investigated for time-dependent thermal annealing with different
morphology evolution scales, having special consideration for the diffusion and aggregation of fullerene derivative molecules
based on blends of poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM). Meaningfully, rapid formation of dot-like and needle-like crystalline PCBM structures
of a few micrometers up to 60 μm in size is obtained with thermal annealing treatment from 2 to 15 min, which dynamically
reflects a fast process of PCBM molecule and cluster aggregation. Upon ultrasonic-assisted processing and annealing treatment,
the scale of P3HT crystals is drastically increased in view of X-ray diffraction (XRD) patterns, leading to a high hole mobility.
And, the P3HT domains can be gradually converted into larger P3HT crystals approved by the decreased full width at half-maximum
in the XRD patterns. Corresponding current–voltage curves are measured in quantity and we propose a model to explain the effect
of the crystalline degree of P3HT domains and aggregation of PCBM molecules and clusters on the phase segregation, expressing
a viewpoint towards high performance of BHJ solar cells. 相似文献
78.
Zhang J Wang M Ge X Wu M Wu Q Yang J Wang M Jin Z Liu N 《Journal of colloid and interface science》2011,353(1):16-21
This paper reports a rapid and facile method of preparing free-standing colloidal crystals from monodisperse charged polystyrene (PS) microspheres. Mixed solvents (ethanol/water) were used as the dispersion medium in the self-assembly process of colloidal crystals. By a simple "floating self-assembly" method, PS microspheres floated on the surface of liquid and self-assembled into large area of three-dimensional (3D) ordered colloidal crystals within 15 min. Then epichlorohydrin was added in as a cross-linking agent to strengthen the colloidal-crystal film. After cross-linking reactions between the microspheres, the obtained colloidal-crystal film was free-standing and could be easily transferred to other substrates. Using tetrabutyl titanate as a titania precursor, 3D porous TiO(2) materials with rodlike skeletal structure were fabricated from the prepared free-standing colloidal crystal. This work provides a facile method to fabricate free-standing colloidal-crystal film, which can be used as an ideal template for the preparation of porous materials. 相似文献
79.
Yutang Liu Xilin Zhang Ronghua Liu Chengbin Liu Qingyun Cai 《Journal of solid state chemistry》2011,184(3):684-689
A new ZnTe modified TiO2 nanotube (NT) array catalyst was prepared by pulse potential electrodeposition of ZnTe nanoparticles (NPs) onto TiO2 NT arrays, and its application for photocatalytic degradation of anthracene-9-carboxylic acid (9-AnCOOH) was investigated. The even distribution of ZnTe NPs was well-proportionately grown on the top surface of the TiO2 NT while without clogging the tube entrances. Compared with the unmodified TiO2 NT, the ZnTe modified TiO2 NT (ZnTe/TiO2 NT) showed significantly enhanced photocatalytic activity towards 9-AnCOOH under simulated solar light. After 70 min of irradiation, 9-AnCOOH was degraded with the removal ratio of 45% on the bare TiO2 NT, much lower than 80%, 90%, and 100% on the ZnTe/TiO2 NT with the ZnTe NPs prepared under the pulsed “on” potentials of −0.8, −1.0, and −2.0 V, respectively. The increased photodegradation efficiency mainly results from the improved photocurrent density as results of enhanced visible-light absorption and decreased hole-electron recombination due to the presence of narrow-band-gap p-type semiconductor ZnTe. 相似文献
80.
Liu B Zhang W Zhang Q Zhang H Yu J Yang X 《Journal of colloid and interface science》2012,375(1):70-77
Hollow porous magnetic microspheres with strong magnetization and controllable structure were prepared via a facile electrostatic self-assembly of the positively charged Fe(3)O(4) nanoparticles onto the surface of the negatively charged poly(N,N'-methylenebisacrylamide-co-methacrylic acid) (P(MBAAm-co-MAA)) microspheres with subsequent removal of the polymer core through calcination at high temperature. The shell thickness was facilely tuned through the ratio between Fe(3)O(4) and polymer, and the void space was conveniently changed through the size of polymer microspheres. The hollow magnetic microspheres possessed high saturation magnetization value (51.38 emu/g) and porous structure with high specific surface area (108.04 m(2)/g). Based on these properties, the drug loading and release behaviors were investigated, which indicated that the hollow magnetic microspheres exhibited a controlled release process. 相似文献